The invention pertains to methods of forming materials having a perovskite-type crystalline structure, methods of forming capacitor dielectrics, capacitor dielectrics produced thereby, and capacitor constructions.
An increasing need exists for reducing the size and increasing the performance of integrated circuit components, for example, dynamic random access memory (DRAM) and non-volatile field effect transistor (FET) memory, as well as other devices. One often common part of integrated circuit components includes dielectric material. Typically, using a dielectric material having a higher dielectric constant K in a capacitor allows storage of the same amount of electrical charge for a given thickness of dielectric with a reduced capacitor area. The increased capacity to store electrical charge provides for fabrication of more advanced transistors. Further, substitution of higher K dielectric can provide improved performance characteristics for a given device. Accordingly, a desire exists to produce higher K materials.
According to one aspect of the invention, a method includes forming a material over a substrate, oxidizing the material, and, separately from the oxidizing, converting at least a portion of the oxidized material to a perovskite-type crystalline structure. As an example, the material can include an alloy of at least two metals. The oxidizing can include exposure to an oxygen plasma and implanting oxygen ions into the material. The converting can include heating the oxidized material and reaching a maximum temperature no more than about one-half of a melting point temperature of the perovskite-type material. The method can further include forming a passivation layer to carbon and nitrogen over the material.
Another aspect of the invention includes forming an alloy material containing at least two metals over a substrate, retarding interdiffusion of the at least two metals, oxidizing the alloy material after retarding interdiffusion, and converting at least a portion of the oxidized alloy material to a perovskite-type crystalline structure. As an example, retarding interdiffusion can include oxidizing at least an outer portion of the alloy material and implanting ions into the outer portion. Also, oxidizing the outer portion and implanting can occur in situ with forming the alloy material. The substrate can include a capacitor electrode and the converted, oxidized alloy material can include a capacitor dielectric layer.
In a further aspect of the invention, a capacitor dielectric forming method includes forming an alloy layer comprising at least two metals over a capacitor electrode, oxidizing the alloy layer, and converting the alloy layer to form a perovskite-type crystalline structure. As an example, at least two of the metals can exhibit a substantial difference in chemical affinity for oxygen. Also, an additional alloy layer can be further converted to an additional capacitor dielectric layer including a perovskite-type crystalline structure.
In a still further aspect of the invention, a capacitor construction includes an inner electrode, an inner dielectric layer over the inner electrode, an outer dielectric layer over the inner dielectric layer, and an outer electrode over the outer dielectric layer. The inner dielectric layer can include an oxidized alloy of at least two metals in a perovskite-type crystalline structure. The outer dielectric layer can include an oxide of a material wherein the material exhibits passivation against carbon and nitrogen reaction. As an example, the capacitor construction can further include a middle dielectric layer between the inner and outer dielectric layers. The middle dielectric layer can include an oxidized alloy of at least two metals in a perovskite-type crystalline structure.